Pressure ulcers also referred as pressure sores are common in patients who are bedridden for a fairly long period and/or may be wheelchair bound. The onset of pressure ulcers can increase hospital stays by as much as 50% or more. For those residing in nursing homes, pressure sores can complicate what should be a restful experience to a punishing stay. For those required to use a wheelchair to get around, pressure ulcers may cause extra inconvenience already being suffered by a patient. All pressure ulcer sufferers are at an increased risk of infection. Pressure ulcers may even lead to sepsis and/or to early death.
Pressure ulcers lesions may start off about one half inch wide and become as large as the size of a palm of a hand or even larger. Surface size is only one measure of the extent of a pressure sore. A pressure sore typically starts at the surface of the skin. If left untreated even for a short time, a pressure sore may extend deep into muscle and/or bone.
Pressure ulcers may be classified into the following stages: Stage 1, a lesion of the epidermis (outer surface of the skin) which is reddish in color on lighter-skinned people and purplish or bluish on dark skinned people. Stage 2 may be a superficial damage to the epidermis with a blister or an abrasion. Stage 3, may be a lesion that extends to subcutaneous tissue, and stage 4 is a lesion that may extend to muscle or bone.
People with reduced ability to move are most susceptible to pressure ulcers. It is believed that pressure ulcers are the result of continuous pressure and/or friction at a particular area of skin, particularly close to bone or cartilage, such as the spine, knees, ankles, heels, back, hips, and coccyx (tailbone).
A number of factors influence the initiation and propagation of pressure ulcers directly or indirectly. For example, the factors may include but are not limited to, pressure, friction, shear, etc. . . . the role of some of the most pertinent factors is as following:
Pressure:
People with reduced ability to move are the most susceptible to pressure ulcers. It is believed that pressure ulcers are the result of continuous pressure and/or friction at a particular area of skin, particularly an area of skin close to bone or cartilage, such as the spine, knees, ankles, heels, back, hips, and coccyx (tailbone).
Estimates are that more than one million people suffer from pressure sores America alone. The numbers of people who will be at risk of suffering from pressure ulcers are likely to increase dramatically because (i) older people are more likely to be involuntarily immobile, (ii) the skin of people tends to thin as they age, and (iii) a large cohort of people are about to start leaving middle age.
Shear
Shearing action occludes blood flow more easily than compression. For example, it is easier to cut off flow in a water hose by bending rather than by pinching it. So it is safe to assume that shear is more significant than normal pressure in promoting pressure ulcers. Areas of the body particularly susceptible to shearing action include ischia tuberosities, heels, shoulder blades and elbows. These are areas of the body are frequently supported when in a position (such as sitting or lying semi-recumbent) which allows forward slide. Superficial pressure ulcers caused by shearing action tend to have uneven appearance.
Friction
Friction, along with normal pressure and shear is also considered to be a cause of pressure ulcers. Friction can cause pressure ulcers both directly and indirectly. In the indirect sense, friction is necessary to generate shearing forces and the skin weakened by pressure ischemia may be more susceptible to friction and the both pressure and shear act together to a relatively quick skin breakdown. Reduced friction prevents further skin breakdown, and helps reduce the risk that an affected area could be further contaminated by the bowel and/or urinary incontinence suffered by some patients. However, healing still is uncertain and may take weeks or even months.
Immobility
Immobility is not a primary cause of pressure ulcers, but in the presence of additional factors it can initiate pressure ulcers. Patients with profound immobility but intact sensation rarely develop pressure ulcers. Conversely, comatose patients, even with intact sensation, can develop pressure ulcer, as they cannot communicate regarding pain of increased pressure threshold. The pain of tissue ischemia ensures that these patients frequently ask for their position to be changed. Patients with orthopedic casts should be encouraged to report any discomfort and pain in order to prevent iatrogenic pressure ulcers.
Failure of Reactive Hyperamia Cycle:
It is a well-known fact that tissue distortion causes ischemia that in turn stimulates protective movements to relieve pressure and circulatory activity to restore normal blood flow in the affected areas. These protective movements are often reflexes as the person is unaware of making them. However, if these prompt actions prove insufficient to relieve ischemia, the central nervous system is stimulated by constant signals of discomfort and pain to make sure that the pressure is relieved before any permanent damage occurs. Once the pressure is relieved, and the circulation restored, local capillaries begin to dilate and increased blood flow takes place, referred to as reactive hyperemia. As a result, a bright pink transitory patch appears on the skin, often called blanching erythema because it blanches on pressure unlike the dull red non-blanching erythema that indicates tissue damage reactive hyperemia ensures a rapid restoration of oxygen and carbon dioxide balance; it also flushes out waste products. Erythema subsides as soon as tissues are restored to their resting state.
The basic measure for treatment and/or prevention of pressure ulcers requires frequent turning by a caregiver of an immobile patient. To some extent, a wheelchair bound person may be able to move the potentially affected portions of his own body by himself. Turning is recommended at least once every two hours. Each time the body is turned, pressure is at least temporarily relieved from the areas previously under pressure and allows them to be air-cooled. However, this cannot qualify as the prevention or treatment of pressure ulcers.
Other measures for preventing and/or treating pressure ulcers may include, having the patient rest on an alternating pressure mattress and/or on an air mattress having an air-permeable surface. The purpose of such mattresses is to temporarily transfer pressure from the pressure ulcer to the nearby parts of the body and to provide airflow to the pressure ulcers, which among other things, could allow for cooling of the affected tissue. Even when mattresses are efficacious, they are expensive to buy and expensive to operate and maintain.
To prevent or alleviate pressure ulcers, various types of cushions and pads have been designed. As some are disclosed in the prior art, for example: U.S. Pat. No. 3,721,232 discloses “a method for treating and/or preventing pressure sores. The method comprises the steps of: applying a cushion in indirect or direct contact with substantially the entire surface of a pressure sore area. The cushion is preferably circular in shape with a diameter between about 1.5 and about 6 times its height. In the preferred embodiment, the cushion has a silicone elastomeric shell, with the portion of the shell intended to be in occlusive contact with the pressure sore having a smooth outer surface. In the preferred embodiment, the cushion is partially filled, and the filling material is silicone gel. The cushion may be held in place by means of a strap, wrap, bandage or similar device.” Some pads are made of foam or gel, and some are filled with air or water. These cushions or pads have a body-contacting surface area which is intended to distribute the pressure from lying on a bed. Some of these pads and cushions are formed with a void, with the pressure ulcers to be positioned over the void. Some of the voids are formed by having the pad or cushion shaped as a donut or ring.”
Another prior art, U.S. Pat. No. 7,982,087 titled: “A wound dressing” discloses a transparent upper layer, an absorbent layer comprising a plurality of apertures arranged in a lattice pattern, and a low adherent wound contact layer provided with a plurality of apertures arranged in a lattice pattern such the apertures of this layer are congruent with the apertures of the absorbent layer.
Another prior art, U.S. Pat. No. 7,141,032 titled: An Apparatus and methods for preventing and/or healing pressure ulcers, discloses “Protective devices to protect a plurality of body parts having a bony portion with a soft tissue layer between the bony portion and an outer skin layer, have an inner surface which conforms to the body part to be protected and are applied to the body part to reduce pressure exhibited at the interface between the bony portion and the soft tissue layer, across the soft tissue and outer skin layers and at the interface between the outer skin layer and a support surface. The protective devices may be made of any material suitable for distributing the weight of the body part over an extended area and volume and may include a mushy material, a hard shell, a hydro absorptive material, and a wound dressing with medication. The body part to be protected includes at least one of the heel, trochanter, knee, sacrum, coccyx, ischium, scapula, elbow, ankle, buttocks and occiput: The protective devices may be secured to the body part directly or via a garment or any other suitable securing means.”
Another prior art, U.S. Pat. No. 5,340,363 titled: Wound Dressing, discloses “a porous hydrophobic, layer adapted to directly contact the wound during use and an adjacent absorbent layer attached to said hydrophobic layer, said hydrophobic layer comprising an elastic net-like porous reinforcing component substantially encapsulated by a soft and elastic hydrophobic gel while retaining the porosity of said reinforcing component, said hydrophobic layer thus including openings which permit wound exudate to pass through said hydrophobic layer to be absorbed by said outer absorbent layer.”
Another prior art, U.S. Pat. No. 5,579,570 titled: Multilayer dressing, comprising a molecular filtration membrane having a maximum pore size in the range of from 0.001 μm to 0.5 μm, and preferably in the range of from 0.01 μm to 0.25 μm. The wound dressings may also comprise an absorbent layer atop the molecular filtration membrane and/or a wound contact layer of wound-friendly bio-absorbable material for contacting the wound. In use, the molecular filtration membrane retains high molecular weight biopolymers and wound healing factors at the wound surface while excluding bacteria and allowing rapid egress of wound exudate through the membrane into the absorbent layer. Wound dressing for use, with exuding wounds, comprising a porous hydrophobic layer adapted to directly contact the wound during use and an adjacent absorbent layer attached to said hydrophobic layer, said hydrophobic layer comprising of an elastic net-like porous reinforcing component substantially completely encapsulated by a soft and elastic hydrophobic gel while retaining the porosity of said reinforcing component, said hydrophobic layer thus including openings which permit wound exudate to pass through said hydrophobic layer to be absorbed by said outer absorbent layer.”
Treatment of pressure ulcers usually requires weeks or months for a successful resolution. Unlike the present invention, the efficacy of the cushions and the pads used in the disclosed above referenced prior art still leaves much to be desired. For example, none of the prior art disclosed above, addresses how to mitigate the effects of normal pressure, or precisely, the distribution of body weight (static and dynamic) of the patient's body part. All other pressure ulcers causing or contributing factors, for example, including but not limited to friction, shear, immobility, or excessive movements of the patient in the bed are sub-set of normal pressure, which is the body weight of the patient (static and dynamic). The soft silicone jell pad, which is an integral part of the multilayer dressing of the present invention, absorbs and uniformly distributes the pressure to other body parts of the patient over an extended surface area, and finally the pressure or body weight of the patient is transferred to the patient's bed and dissipates. The multilayer dressing of the present invention addresses the prevention and treatment of pressure ulcers or chronic wounds more efficiently/effectively than any other prior art disclosed above.